Universal saturation of electron dephasing in three-dimensional disordered metals

Abstract

We have systematically investigated the low-temperature electron dephasing times ${\tau }_{\varphi }$ in more than 40 three-dimensional polycrystalline impure metals with distinct material characteristics. In all cases, a saturation of the dephasing time is observed below about a (few) degree(s) Kelvin, depending on samples. The value of the saturated dephasing time ${\tau }_0$ [$\equiv {\tau }_{\varphi }(T\to 0\mathrm{K})$] falls basically in the range 0.005 to 0.5 ns for all samples. Particularly, we find that ${\tau }_0$ scales with the electron diffusion constant $D$ as ${\tau }_0\sim D^{-\alpha }$, with $\alpha$ close to or slightly larger than 1, for over two decades of $D$ from about 0.1 to 10 cm${}^2$/s. Our observation suggests that the saturation behavior of ${\tau }_{\varphi }$ is universal and intrinsic in three-dimensional polycrystalline impure metals. A complete theoretical explanation is not yet available.

4 pages, 3 eps figures